scholarly journals Differential etching after lithic heat treatment: First results of an experimental study

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Linda Kiers
Keyword(s):  
Heat Treatment ◽  
Hydrofluoric Acid ◽  
Chemical Etching ◽  
Smooth Surface ◽  
Weathering Processes ◽  
Heat Treated ◽  
First Results ◽  
Differential Etching ◽  
Pre Treatment ◽  
Control Samples

The practice of lithic heat treatment creates a combination of initial dull flake scars and subsequent smooth flake scars when the implement is finished after heating. Experiments were done to test the susceptibility of dull and smooth flake scars to etching. The points were etched in 40% hydrofluoric acid for either 40 or 60 seconds. In the 40 seconds experiment, the smooth flake scars of 9 (out of 25) heated points showed less etching than the dull flake scars or no etching at all. These artefacts formed a weathering pattern that is similar to double patina in reworked flints. Ten unheated control samples did not form differential weathering between different generations of flake scars. In the 60 seconds experiment 4 (out of 25) heated points showed some parts of the smooth surface to be less affected. Ten unheated control samples did not form differential weathering. The experiments show that sometimes smooth flake scars are more resistant to etching initially. In Scanning Electron Microscopy, flint artefacts are sometimes pre-treated with hydrofluoric acid. Heat treated flints are susceptible to differential weathering by hydrofluoric acid. Thus, pre-treatment with hydrofluoric acid of heat treated SEM samples can lead to surfaces that are etched to a different extent. The chemical etching in this study does not replicate any natural patination process. How heat treated lithics respond to natural weathering processes cannot be predicted. Further studies should produce natural patination and test selected artefacts in contexts of intentional heat treatment for signs of heating.

scholarly journals A Tem Study of Step Morphology on the Non-Uhv Heat-Treated MgO (100) Surface

1992 ◽  
Vol 280 ◽  
Author(s):  
Simon King ◽  
C. Barry Carter
Keyword(s):  
Heat Treatment ◽  
Chemical Etching ◽  
Preliminary Results ◽  
Deviation Parameter ◽  
Surface Steps ◽  
Heat Treated

ABSTRACTPreliminary results from a study of the morphology of the MgO (100) surface after chemical etching followed by heat-treatment in air are presented. Contrast arising from the surface-steps so formed is found to be strongly dependent on the deviation parameter, suggesting that many of the step-faces are not perpendicular to the (100) foil plane but are, instead, often rather shallowly inclined.

scholarly journals EFFECT OF HEAT TREATMENT ON THE RHEOLOGICAL PROPERTIES AND COLOR OF PUMPKINS (Cucurbita moschate)

2015 ◽  
Vol 33 (1) ◽  
Author(s):  
Keila De Souza Silva ◽  
Carolina Castilho Garcia ◽  
Javier Telis Romero ◽  
Maria Aparecida Mauro
Keyword(s):  
Heat Treatment ◽  
Rheological Properties ◽  
Holding Time ◽  
Convective Drying ◽  
Cucurbita Moschata ◽  
Pre Treatment ◽  
And Control ◽  
Control Samples

B.CEPPA, Curitiba, v. 33, n. 1, p. 87-97, jan./jun. 2015EFFECT OF HEAT TREATMENT ON THE RHEOLOGICALPROPERTIES AND COLOR OF PUMPKINS (Cucurbitamoschate)Keila de Souza Silva*Carolina Castilho Garcia**Javier Telis Romero***Maria Aparecida Mauro****The aim is to investigate the eff ects of stepwise blanching and itscombination with drying on rheological properties and change ofcolor in pumpkins (Cucurbita moschata). 1 cm thick samples wereimmersed in water at 55 °C for diff erent times, followed by diff erentholding times prior to inactivation of the enzyme (97 °C/5minutes).Controled samples were obtained after blanching at 97 °C for 5minutes. The texture and color of the samples were measured and therheological parameters calculated according to the Maxwell model.The results showed that stepwise blanching for 40 minutes with 30minutes of holding time provided samples with equilibrium modulusof elasticity greater than the control samples. These parameterswere used as blanching pre-treatment to convective drying with airat 60 °C and a velocity of 1.5 m/s for diff erent drying times. Stepwiseblanched samples showed fi rmer tissues than control samples afterdrying. There were no signifi cant diff erences in the lightness andredness of stepwise blanched samples and control samples duringdrying.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

“In vitro” and in Animal Model Studies on a Double Virus- Inactivated Factor VIII Concentrate

1995 ◽  
Vol 74 (03) ◽  
pp. 868-873 ◽  
Author(s):  
Silvana Arrighi ◽  
Roberta Rossi ◽  
Maria Giuseppina Borri ◽  
Vladimir Lesnikov ◽  
Marina Lesnikov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Animal Model ◽  
Factor Viii ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Virus Inactivation ◽  
Enveloped Viruses ◽  
Model Studies ◽  
Heat Treated

SummaryTo improve the safety of plasma derived factor VIII (FVIII) concentrate, we introduced a final super heat treatment (100° C for 30 min) as additional virus inactivation step applied to a lyophilized, highly purified FVIII concentrate (100 IU/mg of proteins) already virus inactivated using the solvent/detergent (SID) method during the manufacturing process.The efficiency of the super heat treatment was demonstrated in inactivating two non-lipid enveloped viruses (Hepatitis A virus and Poliovirus 1). The loss of FVIII procoagulant activity during the super heat treatment was of about 15%, estimated both by clotting and chromogenic assays. No substantial changes were observed in physical, biochemical and immunological characteristics of the heat treated FVIII concentrate in comparison with those of the FVIII before heat treatment.

Vanadium Additions to a High-Cr White Iron and its Effects on the Abrasive Wear Behavior.

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3077-3089
Author(s):  
Alexeis Sánchez ◽  
Arnoldo Bedolla-Jacuinde ◽  
Francisco V. Guerra ◽  
I. Mejía
Keyword(s):  
Heat Treatment ◽  
Abrasive Wear ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Wear Behaviour ◽  
White Iron ◽  
Heat Treated ◽  
Bulk Hardness ◽  
Abrasive Wear Behavior ◽  
Vanadium Carbides

AbstractFrom the present study, vanadium additions up to 6.4% were added to a 14%Cr-3%C white iron, and the effect on the microstructure, hardness and abrasive wear were analysed. The experimental irons were melted in an open induction furnace and cast into sand moulds to obtain bars of 18, 25, and 37 mm thickness. The alloys were characterized by optical and electronic microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900°C for 45 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under a load of 60 N for 1500 m. The results show that, vanadium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming primary vanadium carbides; thus, decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 20% for the iron with 6.4%V;but overall CVF content (M7C3 + VC) is constant at 30%. Wear behaviour was better for the heat-treated alloys and mainly for the 6.4%V iron. Such a behaviour is discussed in terms of the CVF, the amount of vanadium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

Use of lime for the upgrading of existing wastewater treatment systems

1994 ◽  
Vol 29 (12) ◽  
pp. 279-282 ◽  
Author(s):  
C. Güldner ◽  
W. Hegemann ◽  
N. Peschen ◽  
K. Sölter
Keyword(s):  
Large Scale ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Chemical Precipitation ◽  
Fatty Acid Production ◽  
German States ◽  
Lime Solution ◽  
First Results ◽  
Pre Treatment

The integration of the chemical precipitation unit which would inject a lime solution into a series of mechanical-biological processes, including nitrification/denitrification, and the sludge treatment are the subject of this project. The essential target is the large-scale reconstruction of a mechanical-biological sewage treatment plant with insufficient cleaning performance in the new German states and the adjustment of the precipitation stage to the unsteady inflow of sewage. First results indicate that the pre-treatment performance could be improved by ≅ 20% and the discharge of concentrations of COD, BOD, N and P could be reduced and homogenized. In addition, experiments on hydrolysis and acidifiability of the pre-treatment sludge have been carried out on a laboratory level with the object of making sources of carbon readily available for denitrification. In the course of the experiment, inhibition of fatty acid production by calcareous primary sludge could not be detected. The characteristics of the sludge, such as draining and thickening were considerably improved by the adding of lime.

scholarly journals Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4366
Author(s):  
Saqib Anwar ◽  
Ateekh Ur Rehman ◽  
Yusuf Usmani ◽  
Ali M. Al-Samhan
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Heat Affected Zone ◽  
Tensile Testing ◽  
Weld Zone ◽  
Alloy 800H ◽  
Weld Joints ◽  
Heat Treated ◽  
Friction Weld

This study evaluated the microstructure, grain size, and mechanical properties of the alloy 800H rotary friction welds in as-welded and post-weld heat-treated conditions. The standards for the alloy 800H not only specify the composition and mechanical properties but also the minimum grain sizes. This is because these alloys are mostly used in creep resisting applications. The dynamic recrystallization of the highly strained and plasticized material during friction welding resulted in the fine grain structure (20 ± 2 µm) in the weld zone. However, a small increase in grain size was observed in the heat-affected zone of the weldment with a slight decrease in hardness compared to the base metal. Post-weld solution heat treatment (PWHT) of the friction weld joints increased the grain size (42 ± 4 µm) in the weld zone. Both as-welded and post-weld solution heat-treated friction weld joints failed in the heat-affected zone during the room temperature tensile testing and showed a lower yield strength and ultimate tensile strength than the base metal. A fracture analysis of the failed tensile samples revealed ductile fracture features. However, in high-temperature tensile testing, post-weld solution heat-treated joints exhibited superior elongation and strength compared to the as-welded joints due to the increase in the grain size of the weld metal. It was demonstrated in this study that the minimum grain size requirement of the alloy 800H friction weld joints could be successfully met by PWHT with improved strength and elongation, especially at high temperatures.

scholarly journals The effect of heat treatment and impact angle on the erosion behavior of nickel-tungsten carbide cold spray coating using response surface methodology

2021 ◽  
Author(s):  
Marios Kazasidis ◽  
Elisa Verna ◽  
Shuo Yin ◽  
Rocco Lupoi
Keyword(s):  
Heat Treatment ◽  
Response Surface Methodology ◽  
Mass Loss ◽  
Tungsten Carbide ◽  
Response Surface ◽  
Spray Coating ◽  
Impact Angle ◽  
Control Factors ◽  
Heat Treated ◽  
The Impact

AbstractThis study elucidates the performance of cold-sprayed tungsten carbide-nickel coating against solid particle impingement erosion using alumina (corundum) particles. After the coating fabrication, part of the specimens followed two different annealing heat treatment cycles with peak temperatures of 600 °C and 800 °C. The coatings were examined in terms of microstructure in the as-sprayed (AS) and the two heat-treated conditions (HT1, HT2). Subsequently, the erosion tests were carried out using design of experiments with two control factors and two replicate measurements in each case. The effect of the heat treatment on the mass loss of the coatings was investigated at the three levels (AS, HT1, HT2), as well as the impact angle of the erodents (30°, 60°, 90°). Finally, the response surface methodology (RSM) was applied to analyze and optimize the results, building the mathematical models that relate the significant variables and their interactions to the output response (mass loss) for each coating condition. The obtained results demonstrated that erosion minimization was achieved when the coating was heat treated at 600 °C and the angle was 90°.

scholarly journals Effect of Heat Treatment on the As-Cast Microstructure and Hardness of NiSi3B2 Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 539
Author(s):  
Gonçalo M. Gorito ◽  
Aida B. Moreira ◽  
Pedro Lacerda ◽  
Manuel F. Vieira ◽  
Laura M. M. Ribeiro
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Casting Process ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Energy Dispersive Microanalysis ◽  
Eutectic Constituent ◽  
Backscattered Electron ◽  
Corrosion And Oxidation ◽  
Cast Microstructure

Cast Ni-Si-B alloys have the potential for high-temperature applications because of their high resistance to wear, impact, corrosion, and oxidation at elevated temperatures due to an appropriate balance of hard phases and austenite that ensures a good compromise between toughness and hardness. In this work, NiSi3B2 specimens, fabricated by the lost-wax casting process, were investigated. Given the complex multiphase cast microstructure, a differential scanning calorimeter (DSC-TGA) analysis was employed to characterize the reactions that occur during solidification and the resulting phases were characterized using scanning electron microscopy (SEM), with energy-dispersive microanalysis (EDS) and backscattered electron (BSE) image and X-ray diffraction (XRD). Due to the presence of hard phases, machining of the Ni-Si-B components can pose additional difficulties. Therefore, the conditions of the solution heat treatment, which might lead to the homogenization of the microstructure, consequently improving its machinability, were also investigated. The results of the heat-treated samples indicated that the dissolution of the eutectic constituent is accompanied by a significant decrease in the hardness (approximately 17%). It is important to emphasize that the solution heat treatments carried out reduced the hardness without affecting the percentage of borides, which will allow improving the machinability without adversely affecting the alloy performance in service.

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